从另一个片段的其他视图控制片段的视图
[英]Control views of fragment from other views of another fragment
问题描述
I am writting a simple example of using fragments. 
我正在写一个使用片段的简单示例。 In main activity, there are two fragments. 在主要活动中，有两个片段。 First fragment has some textviews and second fragment has some buttons. 第一个片段具有一些文本视图，第二个片段具有一些按钮。 When user click on the textview, the text on button will be changed. 当用户单击文本视图时，按钮上的文本将被更改。
The activity_main.xml activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal"
tools:context=".MainActivity" android:background="@drawable/ic_launcher_background">
<fragment
android:id="@+id/MenuFrag"
android:name="www.myapplication.MenuFrag"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="1" />
<fragment
android:id="@+id/ContentFrag"
android:name="www.myapplication.ContentFrag"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_weight="3" />
</LinearLayout>
The MainActivity.java MainActivity.java
package www.application;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
public class MainActivity extends AppCompatActivity implements MenuFrag.IFragmentClickListener{
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
@Override
public void onMenuItemClick(int position) {
ContentFrag content = (ContentFrag) getSupportFragmentManager().findFragmentById(R.id.ContentFrag);
if(content!=null)
content.updateContent(position);
}
}
The menu_frag.xml (first fragment) menu_frag.xml（第一个片段）
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@color/colorPrimaryDark"
tools:context=".MenuFrag">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<TextView
android:id="@+id/tv1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:fontFamily="sans-serif-smallcaps"
android:text="TextView 1"
android:textSize="20sp"
android:typeface="serif" />
<TextView
android:id="@+id/tv2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:fontFamily="sans-serif-smallcaps"
android:text="TextView 2"
android:textSize="20sp"
android:typeface="serif" />
<TextView
android:id="@+id/tv3"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:fontFamily="sans-serif-smallcaps"
android:text="TextView 3"
android:textSize="20sp"
android:typeface="serif" />
<TextView
android:id="@+id/tv4"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:fontFamily="sans-serif-smallcaps"
android:text="TextView 4"
android:textSize="20sp"
android:typeface="serif" />
<TextView
android:id="@+id/tv5"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:fontFamily="sans-serif-smallcaps"
android:text="TextView 5"
android:textSize="20sp"
android:typeface="serif" />
</LinearLayout>
</FrameLayout>
The MenuFrag.java MenuFrag.java
package www.application;
import android.content.Context;
import android.os.Bundle;
import android.support.v4.app.ListFragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ListView;
import android.widget.TextView;
public class MenuFrag extends ListFragment {
IFragmentClickListener itemfragment;
TextView tv1;
private View.OnClickListener onclick = new View.OnClickListener() {
@Override
public void onClick(View v) {
itemfragment.onMenuItemClick(1);
}
};
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.menu_frag, container, false);
tv1= view.findViewById(R.id.tv1);
tv1.setOnClickListener(onclick);
return view;
}
@Override
public void onAttach(Context context) {
super.onAttach(context);
try {
itemfragment = (IFragmentClickListener) context;
}catch(ClassCastException e){e.printStackTrace();}
}
@Override
public void onListItemClick(ListView l, View v, int position, long id) {
itemfragment.onMenuItemClick(position);
}
public interface IFragmentClickListener{
public void onMenuItemClick(int position);
}
}
The content_frag.xml (second fragment) content_frag.xml（第二个片段）
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@color/colorPrimary"
tools:context=".ContentFrag">
<ScrollView
android:layout_width="match_parent"
android:layout_height="match_parent">
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/btmessage"/>
</ScrollView>
</FrameLayout>
The ContentFrag.java ContentFrag.java
package www.application;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
public class ContentFrag extends Fragment {
Button btmessage;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View v = inflater.inflate(R.layout.content_frag, container, false);
btmessage = v.findViewById(R.id.btmessage);
return v;
}
public void updateContent(int position){
btmessage.setText("You clicked !");
}
}
I didn't write the action to control the button, just generate the onclick event. 我没有编写控制按钮的操作，只是生成了onclick事件。 However, I got error. 但是，我得到了错误。 Please help me fix error, and continue completing my task. 请帮助我修复错误，然后继续完成我的任务。
E/AndroidRuntime: FATAL EXCEPTION: main Process: www.myapplication, PID: 21117 java.lang.RuntimeException: Unable to start activity ComponentInfo{www.myapplication/www.myapplication.MainActivity}: android.view.InflateException: Binary XML file line #10: Error inflating class fragment at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2298) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360) at android.app.ActivityThread.access$800(ActivityThread.java:144) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:135) at android.app.ActivityThread.main(ActivityThread.java:5221) at java.lang.reflect.Method.invoke(Native Method) at java.lang.reflect.Method.invoke(Method.java:372) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694) Caused by: an
1 个解决方案
解决方案1
2 已采纳 2018-10-07 14:09:09
The issue is with MenuFrag Fragment , the way you are initializing your TextView . 问题在于MenuFrag Fragment （初始化TextView 。
ie tv1= getActivity().findViewById(R.id.tv1); 即tv1= getActivity().findViewById(R.id.tv1);
Rather I'd suggest to move it to onCreateView() . 相反，我建议将其移至onCreateView() 。 Like this: 像这样：
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.menu_frag, container, false);
tv1 = view.findViewById(R.id.tv1);
tv1.setOnClickListener(onclick);
return view;
}
When you called getActivity().findViewById , It searches for that TextView id in activity's layout which couldn't be found. 当您调用getActivity().findViewById ，它将在活动的布局中搜索找不到的TextView id。
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